Sleep and Metabolic Health
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Stages of Sleep and its Effect on Metabolic Health

Today, it is observed that people are not getting a good amount of sleep, which is essential for the body’s proper metabolism. In contrast to the sleep of 9 hours, which is considered ideal for keeping all the internal functioning of your body at a proper pace, today, most people have only 6.8 hours of sleep.

Metabolism of the body

Hormones and enzymes in our body carry out various biochemical processes to keep the body active and functional. These processes are mainly of two types, namely catabolism and anabolism. Catabolism is the process of breaking down, whereas anabolism means building up. Both these processes together regulate reactions occurring in our body. 

Stages of Sleep

Sleeping does mean only closing your eyes. When you are sleeping, you are going through various stages of sleep. Sleep is classified into four stages- 

1. Awake Stage

This is the initial stage when you have to enter your bed and try to sleep. It can be called the progression of wakefulness towards sleep. This stage lasts for 5-10 minutes, depending on your focus to sleep. 

2. Light Sleep Stage

This lasts for 20 minutes. The body’s temperature lowers, and heart rates start to slow down. Your brain starts to make spiral circles, and you will go into a deeper sleep. 

3. Deep Stage or Non-Rapid Eye Movement Stage (NREM) 

You enter into a deep sleep when your muscles relax, heart rate decreases and blood pressure calms down. This stage is also called the Non-Rapid Eye Movement Stage. (NREM)

4. Rapid Eye Movement Stage (REM)

In this stage, the eyeballs move rapidly, your body relaxes and becomes immobile, the brain becomes more active, and you can experience dreams. Thus, sleeping starts with the awake or try-to-sleep stage and ends with the REM stage. Now, let’s see how deep sleep and REM sleep affect the body’s metabolism. 

Effect of NREM Sleep on Metabolism

  • In this stage, your body calms down and relaxes. It does not make any eye movements, and even the heart rate and blood pressure slow down. Thus, this stage is like a natural medication for your blood pressure. 
  • The blood glucose in the body becomes passive, and its utilisation decreases greatly, which is why you have lower blood sugar levels when you wake up in the morning. This happens in the later stage. 
  • Metabolic rate and brain temperature lower, which helps repair damages that occurred in the awake and metabolically-active stages. 
  • The action of growth hormones increases at the latter stages of NREM sleep. The activity of insulin, one of the hormones, increases, thus ultimately reducing blood glucose usage by the brain. 

Effect of REM Sleep on Metabolism

  • In the REM stage, hormones like testosterone are secreted in the body. Cortisol levels, a primary stress hormone, increase in this stage. 
  • The brain becomes active and decreases the activeness of muscles, thus allowing us to see the dreams safely. Thus, we can say that REM sleep is fundamentally associated with the dreaming state. 
  • Glucose utilisation increases in this stage, which makes us able to dream. This escalated glucose makes our body sensitive to insulin, which is good in the case of type -2 diabetes. (In type-2 diabetes body become insulin resistant)
  • All these activities during REM sleep play a major role in the growth and repair of the body’s muscles. 
  • The more you get REM sleep, the more is the probability that you will have a long life. 

Effects of being a Night Owl or Sleeping Late

  • If you sleep late, you won’t get the deep sleep in the required amount, and there is a chance that you will skip the deep sleep and go into REM sleep. This will have an adverse effect on your insulin activity, as it is activated during the deep sleep stage.
  • The blood sugar level does not decrease to a good amount.
  • Heart rate increases on the next day because of the inability of the body to get deep sleep. 
  • The body cannot repair damages at a faster rate if the sleep is incomplete. 
  • Some inappropriate changes occur in the body’s metabolism. 
  • The blood pressure of the body increases because of high glucose levels.
  • Due to low energy levels, you do not feel fresh the next day.
  • Muscle growth gets affected when we do not get a good amount of sleep. The growth is less than that when we get a good sleep. 
  • Obesity, diabetes, stroke and heart-related issues can occur. 

Getting Good Sleep

  • Always go to bed at a fixed time and wake up at a fixed time.
  • Avoid watching TV or using mobiles at the time of sleeping.
  • Do some exercise regularly so that you will fall asleep easily.
  • Do not eat hefty foods and drink caffeinated beverages.
  • Always keep your bedroom clean and calm. 


Sleep is essential for good metabolic health. There are four sleeping stages: awake, light sleep, deep sleep and REM sleep. If you sleep late, your body will skip the deep sleep stage, the stage that plays a major role in glucose regulation. Therefore, it is prudent for individuals to get at least 8 hours of sleep daily. 

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This website's content is provided only for educational reasons and is not meant to be a replacement for professional medical advice. Due to individual differences, the reader should contact their physician to decide whether the material is applicable to their case.